Tape-wrapping method and apparatus

ABSTRACT

An improvement in a method and apparatus for wrapping polytetrafluoroethylene tape onto the screw threads of fluid conduits for fluid sealing purposes. The wrapping is accomplished during, and in response to, a single up-down cycle of a linear gear rack, and comprises feeding the tape onto the workpiece during the up-stroke of the gear rack, and rotating the workpiece to wrap it with tape during the down-stroke of the gear rack. This provides a significant reduction in the length of stroke required and also in cycle time, over the known device using the down-stroke to accomplish both the feeding and the wrapping.

United States Patent [191 Stauffer TAPE-WRAPPING METHOD AND APPARATUS [75] Inventor: Du Wayne W. Staufier, Fort Wayne,

Ind.

[73] Assignee: Garlock Inc., Palmyra, N.Y.

[22] Filed: Mar. 30, 1971 [21] App]. No.: 129,472

[52] U.S. Cl 242/7.02, 156/189, 156/392,

156/446, 156/543, 226/113, 242/7.23, 242/55 [51] Int. Cl B65h 17/42, B65h 81/00 [58] Field of Search 242/55, 75.3, 7.23,

[56] References Cited UNITED STATES PATENTS 3,125,309 3/1964 Moyano 22/55 8/1956 Tison 226/113 UX 3/1962 Wahlstrom 242/75.3

Primary Examiner-Billy S. Taylor Attorney-Sch0vec & Boston [5 7] ABSTRACT An improvement in a method and apparatus for wrapping polytetrafluoroethylene tape onto the screw threads of fluid conduits for fluid sealing purposes. The wrapping is accomplished during, and in response to, a single up-down cycle of a linear gear rack, and comprises feeding the tape onto the workpiece during the up-stroke of the gear rack, and rotating the workpiece to wrap it with tape during the down-stroke of the gear rack. This provides a significant reduction in the length of stroke required and also in cycle time, over the known device using the down-stroke to accomplish both the feeding and the wrapping.

15 Claims, 2 Drawing Figures PATENTED SEP25|973 FIG. 2

INVENTOR. DuWoyne W. Stuuffer ATTOR NEYS TAPE-WRAPPING METHOD AND APPARATUS CROSS REFERENCE TO RELATED APPLICATION This invention is an improvement over the invention described in U.S. Pat. No. 3,320,342; the disclosure in said U.S. Pat. No. 3,320,342 is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention V This invention relates to tape-wrapping apparatus and method, and in particular to an improved apparatus and method providing faster operation and a smaller machine.

2. Description of the Prior Art The present invention is an improvement in the tapewrapping method and apparatus desdribed in U.S. Pat. No. 3,320,342. In that patent, a linear, reciprocating gear rack is employed that first feeds tape into contact with a workpiece (such as a threaded nipple)'to be wrapped by the tape, and thatthen rotates the workpiece to wrap the tape onto the workpiece. The feeding and rotating are both accomplished during a single updown cycle of the gear rack, and in fact,both steps are accomplished during the down-stroke of the rack. According to the improvement of the present invention, the tape is fed into contact with the workpiece during the up-stroke of the gear rack, leaving the entire downstroke available for rotating the workpiece to wraprit with the tape, thus reducingthe overall length of the stroke of the gear rack and of the pneumatic power cylinder, and also reducing the cycle time for each job.

It is therefore an object of the present invention to provide an improved tape-wrapping apparatus and method, and in particular, to provide a smaller machine that operates faster.

SUMMARY OF THE INVENTION According to the present invention, a workpiece is wrapped with tape during, and in response to, a single up-down cycle of a linear gear rack, by feeding the tape into contact with the workpiece during the up-stroke of the gear rack, and by rotating the workpiece to wrap it with the tape during the down-stroke of the gear rack.

BRIEF DESCRIPTION OF THE'DRAWINGS 300. The basic machine described in U.S. Pat. No. 3,320,342, is the same as that of the present invention, and thus the entire machine need not be described in detail here, but rather reference is hereby made to U.S. Pat. No. 3,320,342, incorporated. herein by reference, for any additional information on the present invention. This invention differs from that described in U.S.

Pat. No. 3,320,342, primarily in the means for feeding the tape 94 into contact with the workpiece (not shown here, but see the nipple 202, removably held on spindle 56, in FIG. 3 of U.S. Pat. No. 3,320,342). In U.S. Pat. No. 3,320,342, this feed means included, for example, the guide block 116, the crank 120, the lever 126 and the pin 143. The description of the tape feed means starts in the patent at column 5, line 9. In addition to the present invention employing a different tape feed means, the knife mechanism shown in FIGS. 1-5 in U.S. Pat. No. 3,320,342 is not used in the present invention. A knife means forms no part of the present invention, and any suitable knife means, including manually cutting, can be used.

With reference now to the drawings, FIG. 1 is a front view of the machine of the present invention and shows a frame 10 on which a tape supply roll (not shown) is mounted for supplying tape 94 to be wrapped onto a workpiece (not shown). The wrapping is accomplished by first feeding the tape 94 to the workpiece and then rotating the workpiece to wrap the tape 94 around it. The feeding and rotating steps in both the present invention and in the invention of U.S. Pat. No. 3,320,342

are accomplished during a single up-down cycle ofa r verticallgear rack 36. The gearirack is preferably driven.

The present invention will be more fullyunderstood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements, and wherein:

. FIG. I is a simplified, schematic front view of themeferred embodiment of the present invention, and corresponds to FIG. 1 of U.S. Pat. No. 3,320,342, and

FIG. 2 is a simplified, schematic rear view of thepreferred embodiment of the present invention, and corresponds to FIG. 2 of U.S. Pat. No. 3,320,342.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT No. 3,320,342. The new elements of the present invention are referred to with reference numerals starting at by a double acting pneumatic power cylinder 30.

In the present invention, the cylinder 30 is mounted on the floor (not shown) of the machine with its piston rod 32 extending upwardly therefrom and connected to a yoke 34 secured, in turn, to the upper end of the gear rack 36, by means not shown. The gear rack 36 always completes its previous cycle with the gear rackin its down position (the up position is shown in FIG. 2). Thus, each up-down cycle includes first an .upward stroke and then a downward strokeThe device deworkpiece to wrap the workpiece described in U.S. Pat.

No. 3,320,342, such means need not be described in detail here. r

Before describing the details of the tape 94 feed means 300 of the present invention, reference will first be made to FIG. 1 and to that part of the feed means of *the present invention that is substantially the same as the corresponding part of the feed means of U.S. Pat. No. 3,320,342. FIG. 1 shows a tape feed block mounted on the frame I0. The feed block 90 has a groove 92 in its upper surface, in which groove 92 the tape 94 travels. The tape 94 is fed to the right as shown in FIG. 1 by means of a tape foot or finger 104, having serrations l08.on its bottom. FIG. 1 corresponds to FIG. 2 in that both show the finger 10.4 after it has just completed feeding the tape to the rotating means (not shown).

The feeding means 300 of the present invention for moving the finger 104 to feed the tape 94, during the upward stroke of the gear rack 36, will now be described in detail. Referring to FIG. 2, the feeding means 300 includes a cam 302 on the lower portion of the gear rack 36 and a yoke 304 having a cam follower 306 (preferably a rotatable wheel) riding on the cam 302. The yoke 304 is mounted on the frame for pivotal movement about a pivot 308, and the cam follower 306 is spring biased into contact with the cam 302 by means of a tension spring 310 connected between the frame 10 and a bifurcated end 312 of the yoke 304. A shaft 106 is connected to the finger 104 and extends through a slot 114 in the frame 10 and then into a slot 314 in the bifurcated end 312 of the yoke 304. In addition, a vertical slide arm 316 is pivotally mounted to the back of the frame 10 at a pivot 318. The shaft 106 is rigidly connected to the slide arm 316 at a point on the slide arm coinciding with the horizontal centerline of the slot 114. The shaft 106 is freely slidable in the slot 114, and the finger 104 is mounted for free arcuate movement on the shaft 106. The slide arm 316 is located approximately perpendicular to the length of the slot 114, and slide arm 316 has a sufficient length that the movement of the shaft 106 is substantially horizontal and paralle to the groove 92.

' From the above description, itwill be seen that during the upward stroke of the gear rack 36, the cam 302, cam-follower 306 arrangement causes the yoke 304 to rotate clockwise (in FIG. 2) about the pivot 308, causing the shaft 106 and the finger 104 to be moved to the left (in FIG. 2), to feed the tape 94 to the right (as viewed in FIG. I).

In addition to the above-described structure, the present invention includes a guide assembly 320 see FIG. 1). The guide assembly 320 includes a support 322 and an idler roller 324 rotataby mounted on the support 322. The guide assembly 320 is rigidly connected to a shaft 326 that extends through the slot 114 and is rigidly connected to the slide arm 316. A small compression spring 328 is positioned between the support 322 and the finger 104, to spring bias the serrations 108 of the finger 104 into contact with the tape 94 in the groove 92.

As the finger 104 moves to the right as viewed in FIG. 1 to feed the tape 94 to the workpiece, the simultaneous movement to the right of the guide assembly 320, releases tension on the tape 94, to aid the finger 104 in feeding thetape 94.

When the gear rack 36 begins its downward stroke, the spring 310 pulls the finger 104 and the guide assembly 320 back to their original position (not shown) to the extreme right (as viewed in FIG. 2). When the tape is being wrapped on the workpiece, it slides with respect to the finger 104; the tape 94 can push the finger 104 out of the way and cause the finger to pivot slightly in a counterclockwise direction, as viewed in FIG. 1, against the force of the small spring 328.

As mentioned above, the present invention does not employ the tape cutting means described in U.S. Pat. No. 3,320,342, because in that device the knife was in the closed position during all of the up-stroke. While any suitable knife can be used in the present invention, including manually cutting the tape, it is preferred to use a knife that is pivoted out of the way except when actually doing the cutting, and that is actuated to do the cutting in response to movement of the gear rack during its down-stroke.

The present invention has the advantage over the machine of U.S. Pat. No. 3,320,342, for example, of being able to wrap workpiece diameter sizes of from Vs to 34 inch, with a power cylinder having only a 4 inch stroke, whereas the device of U.S. Pat. No. 3,320,342 would require a 5 inch stroke for the same job. This is about a 20 percent reduction in cycle time and in total movement.

Throughout the present specification and claims, the term up-down cycle of the gear rack. is intended only to be relative. For example, the apparatus can be mounted upside-down from that shown in the drawings, or even mounted at to that shown. In either case, the terms up-down cycle and forward-return" are intended to also include down-up, right-left, or any other forward-back or back-forward cycles. While a double-acting pneumatic power cylinder 30 is preferred for use in driving the gear rack 36, other motive means can be used. While the wrapping roller means described in U.S. Pat. No. 3,320,342 are preferred, other wrapping means can be used.

The invention has been described in detail with particular reference to the preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. In a tape-wrapping apparatus for wrapping a workpiece with a length of tape by means of a linear gear rack during a single up-down cycle of the gear rack, and including means responsive to movement of said gear rack for feeding tape into contact with said workpiece and means responsive to movement of said gear rack for rotating said workpiece to wrap said tape.

around said workpiece, the improvement wherein:

a. said feeding means comprises means for feeding said tape during the up-stroke of said gear rack, and includes a tape feed block and a movable tape foot in contact with said block for holding a length 'of said tape therebetween, and means responsive to movement of said gear rack in said up-stroke for moving said tape foot relative to said feed block to feed said tape; and wherein b. said rotating means coinprises means for rotating said workpiece during the down-stroke of said gear rack.

2. The apparatus according to claim 1 wherein said moving means includes a cam surface on said gear rack, a yoke including a cam follower at one end thereof and means connecting the other end of said yoke to said tape foot, pivot means on said yoke in between said two ends, and means for biasing said cam follower into contact with said cam.

3. The apparatus according to claim 2 wherein said connecting means comprises said other end of said yoke including a slot, and a pin connected to said tape foot and riding freely in said slot.

4. the apparatus according to claim 3 including an elongated slide arm positioned approximately perpendicularly to the plane of movement of said tape foot and being rigidly connected adjacent one end thereof to said pin, and said slide arm being pivotally connected at the other end thereof for free swinging movement at said one end thereof, for supporting said tape foot shaft in a substantially horizontal plane troughout the movement of said tape foot.

5. The apparatus according to claim 4 including a guide assembly connected to said one end of said slide arm for movement with said tape foot, for releasing tension on said tape during feeding of said tape.

6. The apparatus according to claim 5 wherein said guide assembly includes an idler roller for said tape and including a spring connected between said bobbin assembly and said tape foot for biasing said tape foot toward said tape feed block.

7. The apparatus according to claim 6 wherein said workpiece is a screw threaded member, said tape is polytetrafluoroethylene, and including a double acting pneumatic power cylinder for driving said gear rack.

8. A method for wrapping the threads of a workpiece with a predetermined length of tape during a single forward-return cycle of movement of a linear gear rack comprising: moving a linear gear rack in a forward stroke and feeding a free end of said tape toward and into contact with the workpiece during and in response to said forward stroke of said gear rack, and then moving said linear gear rack in a return stroke and rotating the workpiece, during and in response to said return stroke of said gear rack, a sufficient amount to completely wrap all of said predetermined length of tape onto said workpiece.

9. The method according to claim 8 wherein said feeding step comprises feeding tetrafluorethylene tape onto screw threads of a cylindrical workpiece.

10. The method according to claim 8 wherein said feeding step comprises contacting a portion of said tape between a stationary tape feed block and a movable tape foot and moving said tape foot in response to said forward stroke of said gear rack to move said free end of said tape into contact with said workpiece.

11. The method according to claim 10 wherein said moving step comprises converting movement of said gear rack during said forward stroke to longitudinal movement of said tape foot across said tape feed block from a starting position to an end. position and including returning said tape foot to said starting position during said back stroke of said gear rack.

12. The method according to claim 8 including guiding a relatively long strip of tape that includes said predetermined length of tape, through a guide path, and reducing the length of said guide path simultaneously with said feeding step to reduce tension on said tape during said feeding step.

13. Apparatus for wrapping the threads of a workpiece with a predetermined length of tape during a single forward-retum cycle of movement of a linear gear rack comprising:

a. a linear gear rack;

b. means for moving said gear rack in a forward stroke and then in a return stroke;

c. means for feeding a free end of said tape toward and into contact with the threads of a workpiece during and in response to movement of said gear rack in said forward stroke; and

d. means for rotating a workpiece and for wrapping all of said predetermined length of tape onto the threads of a workpiece, during and in response to movement of said gear rack in said return stroke.

14. The apparatus according to claim 13 including means on said apparatus adjacent said feeding means for removably holding a workpiece having threads to be wrapped with said tape.

15. The apparatus according to claim 13 including means for guiding tape through a guide path from a tape supply to said feeding means, said guiding means including means for reducing the length of said path simultaneously with feeding tape to said workpiece, to

reduce tension on said tape during said feeding step. 

1. In a tape-wrapping apparatus for wrapping a workpiece with a length of tape by means of a linear gear rack during a single updown cycle of the gear rack, and including means responsive to movement of said gear rack for feeding tape into contact with said workpiece and means responsive to movement of said gear rack for rotating said workpiece to wrap said tape around said workpiece, the improvement wherein: a. said feeding means comprises means for feeding said tape during the up-stroke of said gear rack, and includes a tape feed block and a movable tape foot in contact with said block for holding a length of said tape therebetween, and means responsive to movement of said gear rack in said up-stroke for moving said tape foot relative to said feed block to feed said tape; and wherein b. said rotating means comprises means for rotating said workpiece during the down-stroke of said gear rack.
 2. The apparatus according to claim 1 wherein said moving means includes a cam surface on said gear rack, a yoke including a cam follower at one end thereof and means connecting the other end of said yoke to said tape foot, pivot means on said yoke in between said two ends, and means for biasing said cam follower into contact with said cam.
 3. The apparatus according to claim 2 wherein said connecting means comprises said other end of said yoke including a slot, and a pin connected to said tape foot and riding freely in said slot.
 4. the apparatus according to claim 3 including an elongated slide arm positioned approximately perpendicularly to the plane of movement of said tape foot and being rigidly connected adjacent one end thereof to said pin, and said slide arm being pivotally connected at the other end thereof for free swinging movement at said one end thereof, for supporting said tape foot shaft in a substantially horizontal plane troughout the movement of said tape foot.
 5. The apparatus according to claim 4 including a guide assembly connected to said one end of said slide arm for movement with said tape foot, for releasing tension on said tape during feeding of said tape.
 6. The apparatus according to claim 5 wherein said guide assembly includes an idler roller for said tape and including a spring connected between said bobbin assembly and said tape foot for biasing said tape foot toward said tape feed block.
 7. The apparatus according to claim 6 wherein said workpiece is a screw threaded member, said tape is polytetrafluoroethylene, and including a double acting pneumatic power cylinder for driving said gear rack.
 8. A method for wrapping the threads of a workpiece with a predetermined length of tape during a single forward-return cycle of movement of a linear gear rack comprising: moving a linear gear rack in a forward stroke and feeding a free end of said tape toward and into contact with the workpiece during and in response to said forward stroke of said gear rack, and then moving said linear gear rack in a return stroke and rotating the workpiece, during and in response to said return stroke of said gear rack, a sufficient amount to completely wrap all of said predetermined length of tape onto said workpiece.
 9. The method according to claim 8 wherein said feeding step comprises feeding tetrafluorethylene tape onto screw threads of a cylindrical workpiece.
 10. The method according to claim 8 wherein said feeding step comprises contacting a portion of said tape between a stationary tape feed block and a movable tape foot and moving said tape foot in response to said forward stroke of said gear rack to move said free end of said tape into contact with said workpiece.
 11. The method according to claim 10 wherein said moving step comprises converting movement of said gear rack during said forward stroke to longitudinal movement of said tape foot across said tape feed block from a starting position to an end position and including returning said tape foot to said starting position during said back stroke of said gear rack.
 12. The method according to claim 8 including guiding a relatively long strip of tape that includes said predetermined length of tape, through a guide path, and reducing the length of said guide path simultaneously with said feeding step to reduce tension on said tape during said feeding step.
 13. Apparatus for wrapping the threads of a workpiece with a predetermined length of tape during a single forward-return cycle of movement of a linear gear rack comprising: a. a linear gear rack; b. means for moving said gear rack in a forward stroke and then in a return stroke; c. means for feeding a free end of said tape toward and into contact with the threads of a workpiece during and in response to movement of said gear rack in said forward stroke; and d. means for rotating a workpiece and for wrapping all of said predetermined length of tape onto the threads of a workpiece, during and in response to movement of said gear rack in said return stroke.
 14. The apparatus according to claim 13 including means on said apparatus adjacent said feeding means for removably holding a workpiece having threads to be wrapped with said tape.
 15. The apparatus according to claim 13 including means for guiding tape through a guide path from a tape supply to said feeding means, said guiding means including means for reducing the length of said path simultaneously with feeding tape to said workpiece, to reduce tension on said tape during said feeding step. 